Bulletin 54. Geophysical Methods of Exploration and their ...

GEOPHYSICS DEFINED 23
exploitable mineral resources even though the surface geology
was well known. That the work has been a good investment is
indicated by the interest displayed by oll companies in checking
with more cxgetlsive geophysical methods the likely-looking areas
indicated by the State's magnetic investigations; by the adoption
of the mag_)etic method by several of the mining companies in the
state for exploration work, and by the discovery of hitherto unknown
and ufisuspected potential ore-bodies which i_ppear to be
ss large as any now known in the State.
Similar magnetic investigations have been conducted in recent
years by the Alabama Geological Survey, the Sollth Dakota Geological
Survey, the Arkansas Geological Survey and the Mississippi
Geological Survey ; and in the last-nmned State drilling by a
private company on a favorable structure outlined by the Survey
has resulted in the discovery of the first oil pool discovered in
Mississippi. This success has led to _wre prospecting and at the
present time deep wells are bcit_g suuk in Florida and_ Georgia to
investigate structures outlined by geophysical work and believed
to be favorable for the accumulation of oil.
In Texas, Nevada, New Mexico and the Hawaiian Islands, geophysical
methods have been successfully employed by governmental
agencies in the search for ground-water supplies.
The indirect effect of geophysics and subsurface exploration
may be illustrated by Indiana. This State had closed its geological
survey etJrly in this century since it was believed that there
was nothing further to learn about the geology of the State as all
the surface geology had been mapped. The receIlt success of subsurface
exploration iu adjacent Illinois, however, and the discovery
of the large oil resources there has led Indiana to reopen
her geological survey in order to discover something about her
potential underground wealth.
The State of Illinois can also be used as an example of how a
geological survey can serve the people of a State. In Illinois the
geological survey has a technical staff--not counting office and •
laboratory help--of more than fifty specialists. It also maintains
chemical laboratories, physical laboratories, aud other experimental
laboratories in which men work on problems concerning
the natural rcsot_rces of the State such as possible uses for their
eh_ys, sands, shales, limestones, coal and oil. They also work ou
problems relating to production, metallurgical treatment, etc. ; all
this being in addition to the work of mapping both the surface
and subsurface geology. In Illinois if any industry has a problem
in using a natural resource, the State makes that problem its own
NEW JERSEY GEOLOGICAL SURVEY